Electric control mechanism



Aug. 5 1924.

- E. DENNIS ELECTRIC CONTROL MECHANISM Filed April 8, 1922 2 Sheets-Sheet, 1 Q

Aug. 5, 1924.

E. DENNIS ELECTRIC CONTROL MECHANISM 2 Sheets-Sheet 2 I Filed April 8, 1922 nfleni'om Zaw? 7272 26.

Gummy Patented Aug. 5, 1924.

NITED EARL DENNIS, OF DETROIT, MICHIGAN.

ELECTRIC CONTROL MECHANISM.

Application filed. April 8, 1922.

To all whom it may concern:

Be it known that I, EARL DENNIS, citizen of the United States, residing at Detroit, county of Wayne, State of Michigan, have invented a certain new and useful Improvement in Electric Control Mechanism, and declare the following to be a full, clear, and exact description of the same, such as will enable others skilled in the art to which it pertains to make and use the same; reference being had to the accompanying drawings, which form a part of this specification.

My invention relates to safety electric control-mechanism for power driven machines, commonly referred to as automatic machines. The object is to provide simple, eflicient safety control-mechanism for automatic machines, which control mechanism is of such a character that the possibility of injury to the operator of the machine is reduced to a minimum.

A further object is to provide electric control mechanism of the character described which takes care of both hands of the operator during the operation of the machine through requiring the use of both hands of the operator to operate the control mechanism, thereby removing both of the operators hands from the danger zone during th machine operation.

A further object is to provide positive electric control-mechanism. Within the energized circuit for the control-mechanism are positioned two normally open,manuallyoperable control switches, one for each hand of the operator and both of which must be operated before the circuit can be completed.

A further object is to provide electric control-mechanism for an automatic machine which makes use of the well-known operating pedal usually v found on such machines to control the operation of the m achine.

The abov and other objects, together with the details of construction and method of operatic-11 will further appear from the following description, appended claims and accompanying drawings, in which:

Figure 1 is a perspective of a machine table showing my improved attachment secured thereto.

Fig. 2 is a vertical crosssectional view taken on the line 2-2 of Fig. 1.

Fig. 3 is a cross-sectional view taken on the line 3-3 of Fig. 2.

Serial No. 550,621.

Fig. 4 is a vertical cross-sectional view through the magnet casing.

Fig. 5 is a diagrammatic view of theelectrical circuit through the magnet with the operating pedal raised.

Fig. 6 is a diagrammatic view of the same circuit with the operating pedal depressed.

My invention relates to safety electric control mechanism for use with any of the various types of automatic power operated machines. These machines are of various kinds and provided for the performance of many different mechanical operations and embody such well-known types as punch presses, stamping machines, and machines adapted for the performance of boring, drilling and cutting operations of many kinds. Each machine comprises mechanism adapted to perform its intended mechanical operation, and a work table upon which the operator positions the work to be acted upon, and som form of control trippingmechanism generally in conjunction with the pedal or other operable lever adapted to throw the mechanism of the machine into engagement with the prime mover to be driven thereby.

Injury to the operator, particularly to the hands of the operator, is a frequent occurrence in the use of this type of machine. The operator carelessly leaves the hand eX- posed or fails to withdraw it in time, or inserts it in the machine while the pedal is being held down, and an accident results. I have provided control mechanism which monopoliZ-es both hands of the operator during the working of the machine. The work itself is placed in position to be acted upon and then the two manually-operable control members must be actuated before the machine will operate. I have provided for this purpose two normally open, manually-operable electric switches, both of which must be held in the closed position to make the circuit in which they are dis posed before the machine will operate. Further, in this connection, I have also made use of the conventional foot lever which affords a further safeguard and permits easy adaptation of my improved mechanism to the regular equipment in wide use today. It is evident that, if desired, the foot lever might be dispensed with and that the pedal construction might be widely varied within the scope of the claims.

Due to the fact that there are many types of machines to which this mechanism might be attached,.I have merely shown, broken away, a trip rod which in one form or another is conventional to all these machines,

5 and which is here indicated as 10. The work table is indicated as 11 and the operating pedal as 12, which pedal is pivoted at 13 to a leg of the table and is supported in the elevated position by means of a spring 14.

In this position the machine itself is idle.

Carried by the pedal is a casing 15 which encloses electro-magnets 16 provided with an armature 17 which is supported by the trip rod 10. The normal position of the l5 trip rod is such as to hold this armature spaced above the magnets 16, means being provided to hold the trip rod in the upraised position which is conventional practice on all machines of this character. The

armature is provided with a pair of clownwardly-extending cores 18 disposed within the windings of the magnet coils. A magnet is positioned in an electric circuit which comprises a source of energy, such as a bat tery 17, from which extends a lead wire 8 to the coil of the magnet 16, returning to the battery through the line wire 19 in P1 which may be disposed the two manuallyoperable electric switches 20 and 21 above referred to. The operation of these switches serves to energize the coils and draw the armature 17 down thereagainst. The

T? switches themselves nright be of various types, but as here shown each switch is mounted within a block casing 23 which may be secured to the edge of the table by means of a detachable bracket 24. The

movable switch member is positioned within the block and must be depressed to make 40. the contact. It is thereby removed from 7 accidental operation due to the falling of an article thereon.

The switch comprises a push button 25 mounted within a housing 26 held normally open by means of the spring 27, and provided with a transverse contact member 28.

A pair ,of spaced-apart stationary contacts "(29 and 30, leading off from the line wire- 19,

are positioned in the bottom of the housing 26- and depression of the plunger 25 brings the metal conductor 28 into contact with the said points 29 and 30, so as to "make the break in the line' at the switch.

Each switch member is similarly constructed and, as appears from the drawing, both must be held down to complete the circuit.

I have preferred to make my control mechanism dependent not only on the actuation of the two manually-operable switches, but alsonpon the depression of the pedal member 12. As constructed, the machine would be brought into operation irrespective of whether the switches were first operated or the pedal first operated. Completion of the operation would actuate the rod 10 and trip the machine. Ifthe pedal member is first operated the magnet 16 will be carried downwardly. However, it is of such strength that energization of the coils through operation of the two hereinabove 7 mentioned switches will draw the armature downwardly, operating the trip. On the other hand, if the electric switches are first operated, the resulting energization of the coil of the magnet will serve to magnetically lock the armature 17 to the magnet so that the succeeding downward movement of the pedal will also trip the machine. It will, therefore, be seen that there is in the construction here shown a double safety provision requiring the use of both'jhands as well as the foot lever.

- hat I claim is: p

1. In control mechanism for a poweroperated machine having a tripping member, an operating pedal to actuate the tripping member, an electric magnet carried by said pedal, a movable armature carried by said tripping member and adapted to respond to said magnet, an electric circuit in which said magnet is positioned, and a pair of normallyopen, manuallypperab-le switches in said circuit adapted to make the circuit when bothswitches are closed, said switches relatively spaced apart to require use of two handsto' operate. .7

2. The combination, in a power-operated machine having a tripping member and an operating "pedal to actuate the tripping member, of means for magnetically locking said tripping member to operate with said pedal, which means comprises in part an electric circuit having apair of normally open, manually-operable switches disposed therein and adapted to make the circuit whenboth switches are closed and to break the circuit when either switch is'released which switches are relatively spaced apart such a distance as to require employment of two hands to operate them. i 110 .In testimony whereof, I sign this specification. V

V EARL DENNIS. 

